M4Carbine site maintenance will be performed the remainder of this week and the weekend at least. If the site is unavailable, it is only temporary and we encourage you to visit the links of our site sponsors. Thank you for your patience as we continue to make the site better and more user friendly.

If this is your first visit, be sure to
check out the FAQ by clicking the
link above. You may have to register
before you can post: click the register link above to proceed. To start viewing messages,
select the forum that you want to visit from the selection below.

Matech BUIS

When I bought my Colt 6920 it already had a Matech 600 rear sight installed. I attempted to remove it this afternoon and the lock screw wouldn't move and head felt like it started to strip so I stopped the attempt. My question is does this rear sight take a special tool to install and remove. The lock screw looks like a torqz screw (forgive spelling) or an allen head and neaither seems to work, I don't want to damage it. I appreciate any help.

Use some heat

Sometimes these companies use so much loctite it's a pain to break off. So long as there's no plastic around (def remove any optics you have on it) use a hand held torch to slowly heat the nut and break the seal.

The factory screw uses an 1/3 Allen head. It has an oversized head, but thin body, which tends to promote over torqing because the size of the Allen key used.

If you do snap the mounting screw as some of us have, we do make an improved bracket/screw retrofit kit for the Matech BUIS

The screw is rated Grade 8 plus, for reference, the gas key on the bolt carrier is rated Grade 8. The factory screw has some thread locker already applied, it's typically good for 3 to 4 screwing/unscrewing then a new drop of thread locker needs to be applied.